Extruded flints and process for making same



United States Patent 3,219,443 EXTRUDEH) FLINTS AND PROESS FOR MAKING SAME Walter Bungardt, Essen-Bredeney, Germany, assignor to Th. Goldschmidt A.-G., Essen, Germany No Drawing. Filed Mar. 28, 1962, Ser. No. 183,040 Claims priority, applicatiim ggrmany, Nov. 22, 1955, 7 Claims. (Cl. 75-152) This is a continuation-impart of application Serial No. 623,798, filed November 23, 1956, now abandoned.

My invention generally relates to pyrophoric alloys and is more particularly directed to novel pyrophoric alloy compositions suitable for extrusion.

Considered from another aspect, my invention is concerned with an improved and simplified process for the extrusion of fiints from pyrophoric alloy compositions and with the hints obtained thereby.

While fiints for use in cigarette lighters and the like were originally produced by casting methods, such flints have, in recent years, been manufactured by extrusion, as extrusion, of course, increases the plant output, simplifies the manufacture and may be carried out with considerably less expenditure than casting methods. Further, the general quality of extruded fi'ints including the pyrophoric characteristics compare favorably with and are in many respects superior to that of cast fiints. For these reasons, the industry has generally adopted extrusion processes for the production of fiints.

Extruded as well as cast flints consist essentially of cerium (misch metal) iron alloys. However, those skilled in the art will readily realize that an alloy which may produce satisfactory flints by casting is not necessarily suit able as a raw material for extruded flints. This is so because the problems and considerations underlying the extrusion of fiints are entirely different from those prevailing in casting methods. In fact for many decades it was believed that the extrusion of cerium (mi-sch metal) iron alloys was not feasible and in this connection I refer to my US. Patent 2,660,301 wherein I disclosed for the first time a commercially practical extrusion process for flint material and explained the obstacles which have to be overcome.

However, although my basic invention as embodied in said US. patent has been considered and proved to be a revolutionary advance in this particular art, the extrusion of flints from cerium (misch metal) iron alloys is still plagued by some serious problems. The most serious difficulty in the manufacture of hints or flint rods by extrusion from pyrophoric cerium (m-isch metal) iron alloy-s resides in the extremely high extrusion pressure which in present day processes is necessary for extruding the alloy composition through the extrusion die. Pyrophor-ic alloys used for the extrusion of flints ordinarily contain about 4.5 to 40% of iron in addition to the cerium (misc-h metal) and such alloy composition can only be extruded at pressures between 5,000 to 16,000 kg. per square centimeter and at extrusion temperatures between 400-500 C. It is obvious that such high pressures require elaborate and excessively expensive extrusion presses, which moreover are, of course, subjected to considerable wear and tear. As the extrusion tools have to be frequently replaced and/ or repaired, the intended gain and advantage by using extrusion instead of casting methods is therefore considerably negated or offset by the expenditure in apparatus. In this connection, I Wish to state that attempts have previously been made to reduce the extrusion pressure by alloying the basic alloy composition with additional metals. Thus in my own US. Patent 2,792,301 I have disclosed certain metals which under stated conditions facilitate the extrusion.

3,Zi9,443 Patented Nov. 23, 1965 In the production of flints by casting as distinguished from extrusion it has been suggested to add appreciable amounts of copper or zinc to the alloy mixture to increase the resistance of the flints to disintegration. Thus, US. Patents 2,408,400 and 2,389,198, for example, which are concerned with the product-ion of flints by casting, recommend that at least 1.2% of copper are added in add tion to silver, nickel and chromium. I have carried out extensive experiments with this and other alloy compositions intended for casting with a view of ascertaining whether or not the teachings relating to the casting of flints could be beneficially made use of for the purpose of reducing the Working pressure in the extrusion of flints. The results of my experiments are that these prior art casting compositions containing copper, zinc and other metals cannot in fact be extruded and therefore do not contribute anything of value to the extrusion art and particularly have no bearing in the reduction of the extrusion pressure. For the purpose of substantiating this contention, the following should be considered: The extrusion of pyrophoric alloy compositions is by necessity carried out at temperatures at which the billet or ingot to be extruded is in a plastic state. If the optimum extrusion temperature is above the melting point of one or several of the metals of the alloy composition, this metal or metals liquify .and the liquid phase seriously impairs the extrusion proper and in many cases renders extrusion impossible. Thus, for example, I have attempted to extrude the alloy compositions disclosed in U.S. Patents 2,408,400 and 2,389,198 previously referred to, but Was not successful although I increased the extrusion pressure to 35 tons. The reason for my failure was that the composition formed a substantial amount of liquid phase which soiled and blocked the extrusion tools of the press.

It is, accordingly, a primary object of this invention to provide for an alloy composition which may be extruded at considerably lower pressures than Was hitherto pos- .sible.

It is also an object of this invention to provide an extrusion process for the extrusion of flint material which may be carried out at lower pressure values than heretofore.

Another object of the invention is to provide extruded fiints of excellent quality having superior pyrophoric characteristics.

Generally, it is an object of this invention to improve on the art of extruding fiints as hitherto practiced.

Briefly, and in accordance with this invention, I have ascertained that the addition of small amounts of copper, within predetermined limit ranges, to prior art extrusion alloy compositions considerably facilitates the extrusion procedure and permits the extrusion to be carried out at considerably lower pressure values than was hitherto feasible.

In my previous US. Patent 2,792,301, I have already suggested certain measures with a view to decreasing the required pressure for the extrusion procedure. Thus, in the prior patent referred to, I have proposed to admix the basic alloy composition with metals such as titanium, cadmium, magnesium, calcium, aluminum, barium, zirconium or beryllium in predetermined quantities, i.e. 0.3% to 10%, preferably 0.3% to 1%.

I have found that although the admixture of the elements referred to has a most beneficial influence on the reduction of the extrusion pressure, the additional admixture of 0.05 to 0.45% of copper results in a most unexpected and dramatic reduction of the required extrusion pressure. The following Table I shows by way of example the effectiveness of such small admixtures of copper in connection with the addition of magnesium as proposed in my previous patent. A comparison of tests #468211 and #472 of Table I clearly shows that the required working pressure for the extrusion of the binary cerium (misch metal) iron alloy is quite considerably reduced by the addition of 2.1% of magnesium. It will then be noted that tests #473""475 in which copper in the previously indicated range has been additionally added demonstrate that this small copper content in the alloy composition causes a marked further reduction in the required extrusion pressure.

In this connection, it should be emphasized that the upper limit of 0.45 of copper is critical as larger amounts of copper in the alloy composition cause a partial liquification of the basic alloy composition. In this connection I refer to my above remarks and also to German Patent 891,824, where this matter has been dealt with in detail.

I have also ascertained that the other metals as mentioned in my previous Patent 2,792,301, i.e. calcium, beryllium, barium, aluminum, zirconium and titanium if admixed together with 0.05 to 0.45 of copper yield simi- The invention will now be described in connection with a specific example, it being understood, however, that this example is given by way of illustration and not by way of limitation, and that many changes may be performed without departing in any way from the scope and spirit of this invention as recited in the appended claims.

Example 1 This example illustrates test 475 of Table I above.

An alloy composition comprising 78.49% by weight of cerium (misch metal), 19.2% of iron, 2.0% of magnesium and 0.31% of copper was prepared in known manner and cast into billet or ingot form. The alloy billet was thereafter heated to about 480 C. for minutes and the billet was inserted into an extrusion press and was extruded into thin rods of 2 to 6 mm. diameter at an extrusion pressure of 1650 kg. per square centimeter. The extruded rods were thereafter cut down into individual flints of suitable length.

As control, the test was repeated with an alloy ingot which did not contain the magnesium and copper additions. Extrusion only took place at a working pressure of at least 5100 kg. per square centimeter at the same temperature.

Similar tests were carried out to arrive at test results 468a, 472, 473 and 474.

What I claim is:

l. A pyrophoric alloy composition suitable for extrusion essentially consisting of about between 4.5 to 40% of iron, about between 0.3 to 10% of a metal selected from the group consisting of titanium, magnesium, calcium, beryllium, baritmi, aluminum and zirconium, and between 0.05 to 0.45% of copper, the remainder being misch metal.

2. An extruded flint essentially consisting of about between 4.5 to 40% of iron, about between 0.3 to 10% of a metal selected from the group consisting of titanium, magnesium, calcium, beryllium, barium, aluminum and zirconium, and about 0.05 to 0.45% of copper, the remainder being misch metal.

3. An extruded flint essentially consisting of between about 18 to 22% of iron, between about 0.3 to 10% of a metal selected from the group consisting of titanium, magnesium, calcium, beryllium, barium, aluminum and zirconium, and about 0.05 to 0.45% of copper, the remainder being misch metal.

4. A process of producing flint rods by extrusion which comprises extruding a pyrophoric alloy essentially consisting of about between 4.5 to 40% of iron, about between 0.3 to 10% of a metal selected from the group consisting of titanium, magnesium, calcium, beryllium, barium, aluminum and zirconium, and 0.05 to 0.45 of copper, the balance being misch metal at a temperature of between about 400 to 500 C. and at the lowest working pressure at which extrusion is possible.

5. The process as claimed in claim 4, wherein the alloy is preheated before being extruded.

6. The process as claimed in claim 4, wherein the extrusion pressure is between about 1600 and 3200 kg./cm.

'7. In a process of extruding flints from alloy compositions, wherein the alloy composition essentially consists of between about 4.5 to 40% of iron, about 0.3 to 10% of a metal selected from the group consisting of titanium, magnesium, calcium, beryllium, barium, aluminum and zirconium, the remainder being misch metal, and the alloy composition is extruded at a temperature of between about 400500 C., the improvement which comprises incorporating into the alloy composition, prior to extrusion, 0.05 to 0.45% of copper to reduce the required extrusion pressure.

FOREIGN PATENTS 2/1918 France. 10/ 1957 Germany. 11/1952 Great Britain.

DAVID L. RECK, Primary Examiner. 

1. A PYROPHORIC ALLOY COMPOSITION SUITABLE FOR EXTRUSION ESSENTIALLY CONSISTING OF ABOUT BETWEEN 4.5 TO 40% OF IRON, ABOUT BETWEEN 0.3 TO 10% OF A METAL SELECTED FROM THE GROUP CONSISTING OF TITANIUM, MAGNESIUM, CALCIUM, BERYLLIUM, BARIUM, ALUMINUM AND ZIRCONIUM, AND BETWEEN 0.05 TO 0.45% OF COPPER, THE REMAINDER BEING MISCH METAL. 